Bonded valve seat and method

Abstract

An improved method of metallurgically bonding two dissimilar materials to form, for example, a valve seat for an internal combustion engine. The bonding process is coupled by pressing pressure and the application of heat. The process is controlled so that the temperature of the lower melting point material never exceeds its solidus temperature but is close to it. Plastic deformation occurs in the base material but the base material is not liquefied.

What is claimed is: 
     
       1. A cylinder head for an internal combustion engine comprised of a cylinder head casting formed from a first metal and having a flow passage extending therethrough from a valve seat area and a valve seat insert metallurgically bonded to said valve seat area, said valve seat insert being formed from a second metal, said metals having substantially different melting temperatures, the metallurgical bonding being accomplished by the steps of applying pressure and heat to the two metals to force them into engagement, the process being performed so that the temperature of the metals does not exceed the solidus temperature of the metal having the lower melting point. 
     
     
       2. A cylinder head for an internal combustion engine as set forth in claim 1, wherein the metal of the lower melting point is placed in a state of plastic deformation so as to work harden the metal without affecting any substantial alloying between the two metals. 
     
     
       3. A cylinder head for an internal combustion engine as set forth in claim 2, wherein the temperature of the metal having the lower melting point during the bonding process is maintained in a temperature range that is less than the solidus temperature but close to the solidus temperature. 
     
     
       4. A cylinder head for an internal combustion engine as set forth in claim 3, wherein the temperature of the metal having the higher melting point is maintained so as to not exceed the phase transformation temperature of the metal.